Fabrics vary from each other in the sharpness of a crease which may be obtained in steam pressing operations performed on a garment made from the fabric. For example a high quality pure wool structured garment is pressed as one of the final processes in garment manufacturing. The aim of pressing is to give a smooth crisp appearance to the panels and seams of the garment. If during the pressing the seam can not be made flat and sharp, but tends to billow, then it is said to be "blown", seam blowing can make a high quality tool garment unacceptable for sale and is occurring with increasing frequency in light-weight fabrics.
The ability of a seam to press flat is not directly related to other fabric properties but can be modified during finishing. It is important therefore robe able to predict the performance in seam pressing of a fabric prior to cutting so that remedial measures can be taken where required.
If a sample of fabric is conditioned, folded and pressed, and allowed to recover, the angle of the crease can be measured and used to predict whether seam blowing will occur. When this value is related to other fabric properties such as weight and formability, it can be used to predict the overall appearance of the pressed seam.
In devising an appropriate test for predicting the crease setting performance of a fabric, it is necessary to bear in mind that fabric manufacturers will normally not have steam pressing apparatus available to them which is suitable as a test apparatus. Any apparatus that fabric manufacturers may have available, even if usable in a crease setting performance test, is liable to be subject to numerous unpredictable sources of error which would limit the value of the data obtained as a reliable predictor of a fabric's crease setting performance.